JP2018154558A - Method of manufacturing butadiene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method with which acetaldehyde contained in a reaction product gas containing butadiene generated from a raw material gas containing n-butene and oxygen-containing gas can be removed to an extremely trace amount, and loss of butadiene can be reduced.SOLUTION: A method of manufacturing butadiene includes: obtaining reaction product gas containing butadiene by bringing a raw material gas containing n-butene and oxygen-containing gas into contact with a catalyst in a reaction vessel; compressing the obtained reaction product gas containing butadiene into liquefied butadiene gas; and cleaning the liquefied butadiene gas with an amine aqueous solution.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing butadiene. More particularly, the present invention relates to a method for producing butadiene by an oxidative dehydrogenation reaction, and more particularly, to a method for producing butadiene by removing carbonyl compounds as impurities to obtain high-purity butadiene.

  1,3-butadiene (hereinafter also simply referred to as “butadiene”) is a very important basic chemical and is used as a raw material for synthetic rubbers and elastomers. Butadiene has been mainly produced by a method of extracting and separating from a naphtha C4 fraction, but recently, a method for producing butadiene by subjecting n-butene to vapor-phase catalytic oxidative dehydrogenation on the catalyst surface has attracted attention. Yes.

In the gas phase catalytic oxidative dehydrogenation reaction of n-butene, in addition to the target product butadiene, as a by-product containing oxygen, for example, carbonyl compounds such as carboxylic acid, aldehyde, and / or ketone, and, for example, Heterocyclic compounds such as furan are produced.
Of these by-products, compounds having a large boiling point difference between butadiene and by-products and having no azeotropic point can be removed by distillation. However, acetaldehyde, which is one of the by-products, has a small boiling point difference from butadiene and has an azeotropic point, so that it is difficult to remove it by distillation to an amount less than the azeotropic composition.
In addition, since acetaldehyde inhibits the polymerization reaction of butadiene, it is necessary to remove trace amounts of product butadiene.

For example, Patent Documents 1 and 2 disclose a method for removing aldehyde by solvent extraction from a product gas containing butadiene obtained by a gas phase catalytic oxidative dehydrogenation reaction.
Patent Document 3 discloses a method of cooling a product gas containing butadiene obtained by a gas phase catalytic oxidative dehydrogenation reaction with an organic amine aqueous solution.

JP 2013-103896 A International Publication No. 2013/136434 Pamphlet International Publication No. 2012/157495 Pamphlet

  In the methods described in Patent Documents 1 and 2, a large amount of solvent (water) is required to remove an aldehyde to a very small amount, and the problem that the target product, butadiene, dissolves in the solvent and is lost occurs. To do. In order to solve this problem, a process for recovering butadiene from the solvent can be installed to recover butadiene. However, yet another problem that the process becomes complicated occurs.

  Specifically, Patent Document 1 discloses a method in which an aldehyde containing conjugated diene is brought into contact with a solvent having an infinite dilution activity coefficient of aldehyde at 25 ° C. of 6.0 or less and the aldehyde is removed by solvent absorption. Has been. Examples of the solvent include water, methanol, ethanol, propanol, acetone, and 1,4-dioxane. The operating conditions of the absorption tower are determined in consideration of the aldehyde removal rate and the loss rate of the conjugated diene. Has been. When the amount of conjugated diene dissolved in the solvent is large and the loss rate cannot be ignored, a conjugated diene recovery tower is installed and a step of recovering the conjugated diene by extraction operation or distillation operation is required. The method described in Document 1 has a complicated process.

  Patent Document 2 discloses a method in which a gas containing a conjugated diolefin is compressed into a liquefied gas, and this liquefied butadiene gas is washed with water to remove acetaldehyde. This method is excellent in the acetaldehyde removal rate as compared with the case where the gas containing the conjugated diolefin is washed with water in the form of a gas. However, although conjugated diolefin is hardly soluble, it dissolves in water, and a large amount of water is used in the extraction tower (flushing tower) to remove acetaldehyde. The dissolved conjugated diolefin is lost. The present inventor examined a method of washing liquefied butadiene using a small amount of water in a static mixer instead of the washing tower in the method described in Patent Document 2, but as shown in a comparative example described later. Although the loss of conjugated diolefin was small, the efficiency of removing acetaldehyde was reduced.

  Patent Document 3 discloses a method for removing impurities including carbonyl compounds simultaneously with cooling by using an organic amine aqueous solution as a quenching liquid for cooling a reaction product gas. However, this method alone cannot make the concentration of acetaldehyde contained in the reaction product gas sufficiently low.

  The present invention has been made in view of the above problems, and removes acetaldehyde contained in a reaction product gas containing butadiene produced from a raw material gas containing n-butene and an oxygen-containing gas to a very small amount, And it aims at providing the method which can suppress the loss of butadiene.

As a result of intensive studies on the above problems, the present inventors have found that the method of washing liquefied butadiene gas with an aqueous amine solution has high acetaldehyde removal efficiency and low butadiene loss, and completed the present invention. It came to do.
That is, the present invention is as follows.

[1]
a reaction step in which a raw material gas containing n-butene and an oxygen-containing gas are brought into contact with a catalyst in a reactor to obtain a reaction product gas containing butadiene;
A compression step in which the resulting reaction product gas containing butadiene is liquefied butadiene gas;
A cleaning step of cleaning the liquefied butadiene gas with an aqueous amine solution;
A process for producing butadiene.
[2]
The method for producing butadiene according to [1], wherein the amine aqueous solution is an aqueous solution containing hydrazines and / or organic amines.
[3]
The hydrazine is at least one selected from the group consisting of hydrazine, methyl hydrazine, ethyl hydrazine, and phenyl hydrazine, and their hydrochlorides, their sulfates, and their acetates. [2] A process for producing butadiene as described in 1. above.
[4]
The organic amine is at least one selected from the group consisting of monoethanolamine, methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, and t-butylamine, [2] or [3 ] The manufacturing method of the butadiene of description.
[5]
The washing step
A mixing step of supplying the liquefied butadiene gas and the aqueous amine solution to a static mixer;
A separation step of separating the liquefied butadiene gas and the aqueous phase with a decanter;
The process for producing butadiene according to any one of [1] to [4].

  According to the present invention, an acetaldehyde contained in a reaction product gas containing butadiene produced by bringing a raw material gas containing n-butene and an oxygen-containing gas into contact with a catalyst in a reactor can be removed to a very small amount. Loss can be suppressed.

It is a figure which shows an example of the connection of the static mixer used for the manufacturing method of the butadiene of this embodiment, and a decanter. It is a figure which shows another example of the connection of the static mixer used for the manufacturing method of the butadiene of this embodiment, and a decanter. It is a figure which shows roughly an example of the manufacturing apparatus of the butadiene of this embodiment. It is a figure which shows roughly another example of the manufacturing apparatus of the butadiene of this embodiment.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[Production method of butadiene]
The butadiene production method of the present embodiment is a reaction step (hereinafter referred to as [a]) in which a raw material gas containing n-butene and an oxygen-containing gas are brought into contact with a catalyst in a reactor to obtain a reaction product gas containing butadiene. A reaction step, also referred to as step [a]), a compression step in which the resulting reaction product gas containing butadiene is a liquefied butadiene gas (hereinafter also referred to as [e] compression step or step [e]), And it has the washing | cleaning process (henceforth [f] washing | cleaning process and process [f]) which wash | cleans the said liquefied butadiene gas with amine aqueous solution.

In addition to the steps described above, the method for producing butadiene of the present embodiment includes a rapid cooling step for cooling the reaction product gas containing the butadiene (hereinafter also referred to as [b] rapid cooling step or step [b]). An absorption step (hereinafter also referred to as [c] absorption step or step [c]) in which the reaction product gas containing butadiene is absorbed by a solvent, and a gas containing butadiene is diffused from the solvent in which the reaction product gas is absorbed. It is preferable to have one or more selected from the group consisting of a diffusion step (hereinafter also referred to as [d] diffusion step and step [d]).
Furthermore, it is preferable to have a drying step (hereinafter also referred to as [g] drying step, step [g]) for removing moisture from the washed liquefied butadiene gas.
By combining these steps with a known butadiene purification step, butadiene can be produced.

[A] Reaction Step The production method of the present embodiment includes a reaction step in which a raw material gas containing n-butene and an oxygen-containing gas are brought into contact with a catalyst in a reactor to obtain a reaction product gas containing butadiene.

(1) Source gas and oxygen-containing gas The source gas in the present embodiment refers to a gas containing n-butene, which is a monoolefin having 4 carbon atoms. In the raw material gas used in the present embodiment, the concentration of n-butene is preferably 40% by weight or more, more preferably 50% by weight or more, and further preferably 60% by weight or more with respect to the total amount of the raw material gas. .
Specifically, n-butene includes 1-butene and 2-butene. The ratio of 1-butene and 2-butene is not particularly limited, and n-butene in the range of 0 to 100% by weight for 1-butene and 100 to 0% by weight for 2-butene can be arbitrarily used. .
Further, 2-butene includes a trans isomer and a cis isomer, and 2-butene having a ratio of 100 to 0% by weight and 0 to 100% by weight can be arbitrarily used.

The source gas in this embodiment may contain i-butene. The content of i-butene is preferably 10% by weight or less, more preferably 6% by weight or less, and still more preferably 3% by weight or less with respect to n-butene. The lower limit of the i-butene content is ideally 0% by weight, but may be greater than 0% by weight.
In addition, the source gas in the present embodiment may include one or more selected from the group consisting of n-butane, i-butane, hydrocarbons having 3 or less carbon atoms, and hydrocarbons having 5 or more carbon atoms. Good.

  The raw material gas in the present embodiment is, for example, a C4 fraction by-produced by fluid catalytic cracking (hereinafter also referred to as “FCC”) of a residual component obtained by extracting butadiene from a C4 fraction by-produced by naphtha pyrolysis and a heavy oil fraction. Or i-butene is reacted with water to form t-butyl alcohol (hereinafter also referred to as "TBA") from the C4 fraction produced as a by-product in the catalytic conversion reaction of ethylene or ethanol, i- A method of reacting butene with methanol to give methyl-t-butyl ether (MTBE), a method of reacting i-butene with ethanol to give ethyl-t-butyl ether (ETBE), or a dimerization reaction of i-butene It can be obtained by separating i-butene through a method of forming a compound having 8 carbon atoms.

  The source gas in this embodiment does not necessarily have to be highly pure, and any mixture or industrial grade can be used. Examples of the source gas in this embodiment include a residual component obtained by extracting butadiene from a C4 fraction by-produced by naphtha pyrolysis (hereinafter also referred to as “BBS”), and a residual component obtained by further separating i-butene from BBS ( Hereinafter, it is also referred to as “BBSS”.), C4 fraction by-produced by fluid catalytic cracking of heavy oil fraction, and residual component from which i-butene is further separated, n-butane dehydrogenation reaction or oxidative dehydrogenation reaction C4 component obtained, n-butene obtained by dimerization of ethylene, C4 component obtained by catalytic conversion reaction of ethylene or ethanol, and residual component obtained by further separating i-butene from it. it can. As for said source gas, only 1 type may be used and 2 or more types may be used in combination.

i-Butene can be separated from the raw material gas by, for example, TBA conversion by hydration reaction, MTBE conversion by alcohol reaction, ETBE conversion, selective adsorption, dimerization, or the like, or skeletal isomerization to n-butene. Can be made.
Examples of ethylene that can be used include those obtained by naphtha pyrolysis, ethane pyrolysis, ethanol dehydration, and the like.
As ethanol, for example, industrial ethanol, biomass ethanol, or the like can be used. Biomass ethanol is ethanol obtained from plant resources, and is not specifically limited. For example, ethanol obtained by fermentation of sugarcane, corn, etc., wood such as waste wood, thinned wood, rice straw, and crops Examples include ethanol obtained from resources.

  From the viewpoint of productivity of butadiene, the n-butene concentration in the raw material gas is preferably 2% by volume or more with respect to a total of 100% by volume of the raw material gas and the oxygen-containing gas, 30 volume% or less is preferable. The n-butene concentration in the raw material gas is more preferably 3 to 25% by volume. When the n-butene concentration in the raw material gas is higher than 30% by volume, accumulation of reaction products and coke deposition increase, and the catalyst life tends to be shortened due to catalyst deterioration.

  The oxygen-containing gas refers to a gas containing oxygen. Usually, air is used, but oxygen concentration is higher than air by mixing oxygen with air, etc., or by mixing air with an inert gas such as helium or nitrogen. It is also possible to use a gas with a reduced value.

  The raw material gas containing n-butene and the oxygen-containing gas may contain one or more selected from the group consisting of paraffin, water, steam, hydrogen, nitrogen, carbon dioxide, carbon monoxide and the like. Examples of paraffin include methane, ethane, propane, butane, pentane, hexane, heptane, octane, and nonane. Moreover, after separating the target product butadiene from the reaction product, at least a part of the unreacted n-butene can be recycled to the reactor.

(2) Reactor For the production of butadiene by the catalytic oxidative dehydrogenation reaction of n-butene, a fluidized bed reactor, a fixed bed reactor, a moving bed reactor or the like can be employed. As the reactor, a fluidized bed reactor is preferable because the catalyst can be easily extracted and added.

The fluidized bed reactor has, as main components, a reactor, a gas disperser provided therein, an insert for maintaining a good flow state, and a cyclone, and is previously accommodated in the reactor. It has a structure in which the catalyst is made to flow by an air flow and is in contact with a gas that is a raw material. As the fluidized bed reactor, for example, a fluidized bed reactor described in a fluidized bed handbook (published by Baifukan Co., Ltd., 1999) or the like can be used. is there. The generated heat of reaction can be removed using a cooling pipe inserted in the reactor.
The cooling pipes are arranged in a rich layer and a lean layer in the reactor, and are operated to achieve a target temperature. The rich layer is a region where the catalyst layer density in the lower part of the reactor is high, and the lean layer is a region where the catalyst layer density in the upper part of the reactor is low.

(3) Reaction conditions A raw material gas containing n-butene and an oxygen-containing gas are supplied to the reactor.
The molar ratio of oxygen to n-butene is preferably 0.4 to 2.0, more preferably 0.6 to 1.5, when expressed as oxygen substance amount / n-butene substance amount. More preferably, it is 0.7-1.2. When the molar ratio of oxygen to n-butene is 2.0 or less, the decomposition reaction of the produced butadiene tends to be suppressed. When the molar ratio of oxygen to n-butene is 0.4 or more, the reactivity of n-butene tends to be improved.

  The method for introducing the raw material gas containing n-butene and the oxygen-containing gas into the reactor is not particularly limited. As a method of introducing the raw material gas containing n-butene and the oxygen-containing gas into the reactor, the raw material gas containing n-butene and the oxygen-containing gas are mixed in advance and introduced into the reactor filled with the catalyst. It may also be introduced independently. Further, the raw material gas containing n-butene and the oxygen-containing gas used for the reaction can be heated to a predetermined reaction temperature after being introduced into the reactor, or can be preheated and introduced into the reactor. In order to continuously and efficiently react the raw material gas containing n-butene and the oxygen-containing gas to be subjected to the reaction, it is usually preferable to preheat and introduce it into the reactor.

The reaction temperature is preferably 300 to 420 ° C. By setting the reaction temperature to 300 ° C. or higher, conversion of n-butene tends to occur. By setting the reaction temperature to 420 ° C. or lower, the combustion decomposition of the produced butadiene tends to be kept low. The reaction temperature is more preferably 300 to 400 ° C, still more preferably 310 to 390 ° C.
The reaction temperature can be adjusted to the above range by removing the heat of reaction using a cooling pipe or supplying heat using a heating device. Since the oxidative dehydrogenation reaction of n-butene is an exothermic reaction, it is usually preferable to perform heat removal so that a suitable reaction temperature is obtained.

The reaction pressure is not particularly limited, and can be performed at a slightly reduced pressure to 0.8 MPaG.
The contact time between the raw material gas containing n-butene and the oxygen-containing gas supplied to the reactor and the catalyst is preferably 0.5 to 20 (sec · g / cc), more preferably 0.6 to 10 (sec. G / cc), more preferably 0.8 to 8 (sec · g / cc). The contact time is defined by the following equation. When the contact time is 0.5 (sec · g / cc) or more, the conversion of n-butene tends to be sufficiently high. When the contact time is 20 (sec · g / cc) or less, butadiene overreaction tends to be suppressed.

(Wherein, W is the catalyst charge (g), F is the total flow rate of the raw material gas and the oxygen-containing gas (NL / hr, NTP conversion value (value converted to 0 ° C., 1 atm)), and T is the reaction temperature (° C. ), P represents the reaction pressure (MPaG).)

By contacting the catalyst, the raw material gas, and the oxygen-containing gas in the reactor, butadiene is produced from n-butene, and the reaction product gas containing butadiene flows out from the reactor outlet.
The oxygen concentration in the reaction product gas at the reactor outlet is preferably maintained at 0.01 to 3.0% by volume, more preferably 0.05 to 2.0% by volume, and 0.10 to 1%. More preferably, it is maintained at 8% by volume.
By maintaining the oxygen concentration in the reaction product gas at the outlet of the reactor within the above range, reduction of the catalyst and decomposition of the target product in the reactor can be effectively prevented, and butadiene can be produced stably. The oxygen concentration in the reaction product gas at the outlet of the reactor is preferably maintained at 3.0% by volume or less because it affects the decomposition and secondary reaction of butadiene in the reactor.
The oxygen concentration in the reaction product gas at the outlet of the reactor is the amount of n-butene contained in the raw material gas supplied to the reactor, the amount of oxygen-containing gas serving as an oxygen supply source, the reaction temperature, the pressure in the reactor, the catalyst It can be controlled by adjusting the amount, the total amount of gas supplied to the reactor, and the like. The oxygen concentration in the reaction product gas at the outlet of the reactor is preferably adjusted by controlling the amount of oxygen-containing gas, for example, air, which serves as an oxygen supply source supplied to the reactor.
The oxygen concentration in the reaction product gas at the outlet of the reactor can be measured by using a gas chromatography equipped with a thermal conductivity detector (TCD) or a galvanic cell type oxygen concentration meter.

(4) Catalyst Hereinafter, the catalyst used in this embodiment will be described.
The catalyst used in the present embodiment is a catalyst in which an oxide is supported on a support from the viewpoint of obtaining butadiene with a relatively high yield by a fluidized bed reaction, and a catalyst containing Mo, Bi and Fe is preferable. The compositions of Mo, Bi and Fe are adjusted so as to form a desired oxide, and it is considered that oxidative dehydrogenation of butadiene from n-butene is performed by lattice oxygen in the oxide.
The carrier is preferably silica, alumina, titania or zirconia, more preferably silica. Silica is an inert carrier compared to other carriers, and has a good binding action with the catalyst without reducing the activity and selectivity of the catalyst with respect to the target product. In addition, by supporting the oxide on silica, physical properties suitable for a fluidized bed reaction such as particle shape, particle size, particle distribution, fluidity, and mechanical strength can be imparted.

[B] Rapid Cooling Process The production method of the present embodiment preferably includes a rapid cooling process for cooling the reaction product gas containing butadiene obtained in the above [a] process. In the quenching step, the reaction product gas is fed into the quenching tower from the bottom and rises in the quenching tower. Since the quenching liquid is sprayed in the quenching tower, the reaction product gas comes into contact with the quenching liquid, is cooled and washed, and is distilled from the top of the tower.

In the rapid cooling step, the removal target component contained in the reaction product gas is removed simultaneously with the cooling of the reaction product gas containing butadiene. Specifically, the physical absorption that dissolves the component to be removed in the quenching liquid, and the chemical absorption that is converted into a component having a very low vapor pressure by the chemical reaction between the removing agent contained in the quenching liquid and the component to be removed. Can also be removed.
Here, the component to be removed refers to reaction by-products such as carboxylic acids, aldehydes, ketones, aromatic compounds, heterocyclic compounds and the like.

The quenching tower is preferably a multistage quenching tower having two or more sections, and more preferably a multistage quenching tower having three or more sections from the viewpoint of efficiently bringing the quenching liquid into contact with the reaction product gas containing butadiene.
In the quenching tower, the quenching liquid extracted in each section is sprayed as a circulating liquid (hereinafter referred to as “circulating liquid”) above the extraction position to cool the reaction product gas containing butadiene and remove the components to be removed. After removal, it is extracted from each compartment. On the other hand, the reaction product gas containing butadiene distilled from the top of the quenching tower is sent to the next step. The extracted quenching liquid is preferably re-sprayed as a circulating liquid after cooling.

  [C] In order to reduce the load of the degassing operation of the inert gas in the absorption step, the outlet gas temperature of the quenching tower is preferably controlled to an appropriate temperature. As a method for this control, it is effective to cool the quenching liquid to an appropriate temperature before re-spraying and supply it to the upper stage of the quenching tower. At this time, the temperature of the quenching liquid is preferably controlled to 80 ° C. or less, more preferably 0 to 70 ° C. The gas temperature at the exit of the quenching tower is preferably controlled to 70 ° C. or lower, more preferably 30 to 60 ° C.

  The pressure in the quenching tower is preferably 0.01 to 0.4 MPaG, more preferably 0.02 to 0.3 MPaG, and still more preferably 0.03 to 0.2 MPaG.

When an aqueous solution is used as the quenching solution, it is preferable to use an aqueous solution of a nitrogen-containing compound, particularly an organic amine. When an aqueous solution of organic amine is used as the quenching solution, there is an advantage that the discharged waste organic amine aqueous solution can be incinerated as it is.
Examples of the organic amine used in the aqueous solution include monoethanolamine, diethanolamine, triethanolamine, methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, t-butylamine, dimethylamine, diethylamine and dipropyl. Amine, trimethylamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamineamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-ethyldiethanolamine Nn-butylethanolamine, Nn-butyldiethanolamine, Nt-butylethanolamine, Nt-butyldiethanolamine, etc. . Said organic amine can be used 1 type or in combination of 2 or more types.
Among the above organic amines, an organic amine having a hydroxyl group is preferable, monoethanolamine, diethanolamine, and triethanolamine are more preferable, and monoethanolamine is more preferable.
Carboxylic acid and aldehydes in the reaction product gas containing butadiene can be removed by using an organic amine aqueous solution as the quenching solution, but acetaldehyde in the butadiene gas cannot be reduced to a sufficient amount in the quenching process. .

When an organic solvent is used for the quenching liquid, an aliphatic and / or aromatic hydrocarbon solvent can also be used. Examples of the aliphatic and / or aromatic hydrocarbon solvent include C6 or higher saturated hydrocarbon, C6 or higher alkyl-substituted aromatic hydrocarbon, and the like.
As the aliphatic hydrocarbon, for example, one or more selected from the group consisting of cyclohexane, heptane, octane, nonane, decane, undecane, dodecane, and structural isomers thereof are preferable.
As the aromatic hydrocarbon, for example, one or more selected from the group consisting of benzene, toluene, o-xylene, m-xylene, p-xylene, mixed xylene, ethylbenzene, trimethylbenzene, cumene, pseudocumene are preferable, Toluene, o-xylene, m-xylene, p-xylene, mixed xylene, ethylbenzene alone or a mixture thereof is more preferable.

  In addition to the organic amine aqueous solution and the aromatic solvent, quenching may be performed using water as a quenching liquid independently for each section of the quenching tower.

Each compartment may be provided with empty towers, trays, packings, etc. for the purpose of adjusting the gas-liquid contact efficiency.
A spray nozzle can be used for spraying the circulating liquid, and the number and arrangement of empty towers, trays, and packings may be determined appropriately in consideration of contact between the liquid and gas.

[C] Absorption process It is preferable that the manufacturing method of this embodiment includes the absorption process which makes the solvent absorb the reaction product gas containing butadiene. By absorbing the gas containing butadiene in a suitable solvent, a solution that easily separates the gas containing butadiene can be obtained in the subsequent diffusion step. In addition, the inert gas contained in the reaction product gas containing butadiene during the absorption process is removed.

  Examples of the solvent that absorbs a gas containing butadiene (hereinafter, also referred to as “absorbing solvent”) include linear or cyclic hydrocarbons and aromatic hydrocarbons. Moreover, the compound used as these solvents may further be a compound having a substituent. Specific examples include octane, nonane, decane, ethylcyclohexane, octene, nonene, toluene, ethylbenzene, xylene, cumene, trimethylbenzene, vinylcyclohexene, furfural and the like. Among the above, octane, nonane, decane, ethylcyclohexane, toluene, m-xylene, o-xylene, p-xylene, mixed xylene, ethylbenzene, and trimethylbenzene are preferable. As for said absorption solvent, only 1 type may be used and 2 or more types may be used in combination.

In the step [c], for example, the reaction product gas containing the cooled butadiene obtained in the step [b] is introduced into the bottom of the absorption tower, and the absorption solvent is brought into countercurrent contact in the absorption tower, thereby butadiene. And other hydrocarbons mainly composed of C4 components are absorbed into the absorbing solvent from the reaction product gas. Step [c] may be performed after the reaction product gas containing butadiene is compressed and cooled.
As an absorption tower, towers, such as a packed tower and a plate tower, can be used, for example.

  In order to further increase the butadiene absorption efficiency in the absorption solvent, it is also one of preferred embodiments to cool a part of the liquid in the absorption tower with a cooler.

  The absorption solvent containing butadiene extracted from the bottom of the absorption tower is preferably introduced into the diffusion step of step [d].

[D] Dissipation process It is preferable that the manufacturing method of this embodiment performs the diffusion process which diffuses the gas containing butadiene from the absorption solvent containing butadiene after the said process [c]. In the diffusion step, the gas component containing butadiene is gasified from the absorbing solvent containing butadiene, and the absorbing solvent is separated and recovered.

The absorbing solvent containing butadiene is preferably introduced into the middle stage of the stripping tower.
The pressure in the stripping tower is preferably 0.01 to 0.6 MPaG, more preferably 0.03 to 0.5 MPaG.
The top temperature of the stripping tower is preferably 0 to 90 ° C.
The bottom temperature of the stripping tower is preferably 100 to 190 ° C, more preferably 110 to 180 ° C. By setting the tower bottom temperature to 100 ° C. or higher, hydrocarbons such as butadiene can be sufficiently diffused. By setting the tower bottom temperature to 190 ° C. or lower, thermal polymerization of butadiene, generation of dirt and tar can be prevented.
As the stripping tower, a packed tower or a plate tower can be used.

The gas containing butadiene is recovered from the top of the stripping tower, and the absorbing solvent containing almost no butadiene is extracted from the bottom of the tower. Since the extracted absorption solvent can be recycled to the absorption process and subsequently used, it is preferable to supply it to the top of the absorption tower.
In the case where a high boiling point component removed from the reaction product gas, dirt, tar, or the like accumulates in the absorbing solvent after a long period of use, it is one of preferred embodiments to purify the absorbing solvent continuously or intermittently.
Moreover, it is preferable to add a polymerization inhibitor to the absorbing solvent in advance from the viewpoint of preventing the absorption solvent from producing dirt and tar. Examples of the polymerization inhibitor include hydroquinone, 4-methoxyphenol, phenothiazine, 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-hydroquinone, 4-t-butylcatechol, Bisphenol A etc. are mentioned. The above polymerization inhibitors can be used alone or in combination of two or more.

[E] Compression Step The manufacturing method of the present embodiment includes a compression step in which the reaction product gas containing butadiene obtained is liquefied butadiene gas. In the compression step, for example, the reaction product gas containing butadiene introduced from the step [a] or the step [d] is cooled and / or compressed to obtain a liquefied butadiene gas.

Cooling for compressing the reaction product gas containing butadiene can be performed by a cooler.
The temperature in a cooler becomes like this. Preferably it is -1-60 degreeC, More preferably, it is 0-50 degreeC, More preferably, it is 5-45 degreeC. The effect which suppresses the freezing in piping is acquired by making the temperature in the said cooler into -1 degreeC or more. By setting the temperature in the cooler to 60 ° C. or less, the reaction product gas containing butadiene can be sufficiently compressed to obtain a liquefied butadiene gas.
The cooler is not particularly limited as long as it can be adjusted to the above temperature. For example, a shell-and-tube heat exchanger or the like can be used.

The reaction product gas containing butadiene can also be compressed by a compressor.
The pressure in compression is preferably 0.01 to 1.0 MPaG, more preferably 0.05 to 0.8 MPaG, and still more preferably 0.1 to 0.6 MPaG. By setting the pressure to 0.01 MPaG or more, the reaction product gas containing butadiene can be sufficiently compressed, and a liquefied butadiene gas can be obtained. By setting the pressure to 2.0 MPaG or less, the effect of reducing the energy cost can be obtained.
The compressor is not particularly limited as long as it can be adjusted to the above-mentioned pressure. For example, a turbo compressor, a volume compressor, or the like can be used.

[F] Cleaning Step The manufacturing method of this embodiment includes a step of cleaning the liquefied butadiene gas with an aqueous amine solution. Specifically, for example, by contacting the liquefied butadiene gas obtained in the above step [e] with an aqueous amine solution, the acetaldehyde in the liquefied butadiene gas is removed to an extremely small amount, and the liquefied butadiene gas is washed. I do. In addition, carbonyl compounds other than acetaldehyde can be removed by the washing step.

  For the washing step, for example, a static mixer, an extraction tower, a stirring mixer, or the like can be employed. From the viewpoint of further suppressing butadiene loss due to dissolution of butadiene in an aqueous amine solution, it is preferable to use a static mixer. The type of the static mixer is not particularly limited, but it is preferable to use, for example, a line mixer.

The pressure in the step [f] is preferably 0.25 to 0.70 MPaG, more preferably 0.30 to 0.60 MPaG, and still more preferably 0.35 to 0.55 MPaG.
The operating temperature in the step [f] is preferably 0 to 45 ° C, more preferably 5 to 30 ° C, and further preferably 5 to 20 ° C. Freezing in piping can be suppressed because the operation temperature in process [f] is 0 ° C or more. Extraction efficiency can be made high by the operating temperature in process [f] being 45 degrees C or less.

When a static mixer is used in the cleaning process, it is preferable to mix the liquefied butadiene gas and the aqueous amine solution and supply the mixed mixture to the static mixer. In the static mixer, acetaldehyde and amine react to remove a trace amount of acetaldehyde in the liquefied butadiene gas.
The ratio of the supply amount of the aqueous amine solution (g / Hr) to the liquefied butadiene gas is preferably 0.1 to 5.0, more preferably 0.2 to 3.0, and still more preferably 0, where the liquefied butadiene gas is 1. .4 to 2.0. By setting the ratio to 0.1 or more, the reaction between acetaldehyde and an amine proceeds sufficiently, and acetaldehyde can be efficiently removed. By making the ratio 5 or less, the amine consumption tends to be suppressed.
The concentration of the amine in the aqueous amine solution is 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, and still more preferably 0.1 to 3.0% by weight. By setting the concentration of the amine to 0.01% by weight or more, the reaction between acetaldehyde and the amine proceeds sufficiently, and acetaldehyde can be efficiently removed. By setting the concentration of the amine to 10% by weight or less, the amine consumption tends to be suppressed.

The amine in the aqueous amine solution in the present embodiment is not particularly limited as long as it is a compound having at least one amino group.
Amine easily reacts with acetaldehyde, and the reaction product of amine and acetaldehyde has a high boiling point, so that it is easily separated from butadiene.
The aqueous amine solution is preferably an aqueous solution containing hydrazines and / or organic amines. In particular, hydrazine has a strong reducibility, and therefore has a high reaction rate with carbonyl compounds such as acetaldehyde and reacts with acetaldehyde to produce hydrazone. Since the produced hydrazone reacts with acetaldehyde to produce azine, 2 equivalents of acetaldehyde react with hydrazine. Therefore, since it is possible to efficiently remove acetaldehyde with a small amount of hydrazine, the aqueous amine solution is more preferably an aqueous solution containing hydrazine.

  Preferred examples of the hydrazines include hydrazine, methyl hydrazine, ethyl hydrazine, and phenyl hydrazine, their hydrochlorides, their sulfates, and their acetates. These can be used alone or in combination of two or more.

Examples of organic amines include monoethanolamine, diethanolamine, triethanolamine, methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, t-butylamine, dimethylamine, diethylamine, dipropylamine, trimethylamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamineamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-ethyldiethanolamine, Nn -Butylethanolamine, Nn-butyldiethanolamine, Nt-butylethanolamine, Nt-butyldiethanolamine and the like. These can be used alone or in combination of two or more.
Among the above organic amines, monoethanolamine, methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, and t-butylamine are preferable.

  FIG. 1 is a diagram showing an example of an apparatus for cleaning the liquefied butadiene gas 1 with an aqueous amine solution 5 in the present embodiment. The liquefied butadiene gas 1 and the aqueous amine solution 5 are mixed and supplied to the static mixer 3. The reaction product of amine and acetaldehyde containing water and liquefied butadiene gas flow out from the outlet of the static mixer 3 and are supplied to the decanter 2 for oil-water separation. The liquefied butadiene gas 6 after removal of acetaldehyde, which is an oil phase, is supplied to the next step, and the aqueous phase containing the reaction product of amine and acetaldehyde is treated as waste liquid 4. As shown in FIG. 2, the oil phase and the water phase may be recycled. The liquefied butadiene gas that is an oil phase may contain a reaction product of an amine and acetaldehyde, and the reaction product of such an amine and acetaldehyde is the next step, step [g] or step [ h] and the like can be further removed.

  That is, the cleaning step in the present embodiment includes a mixing step of supplying the liquefied butadiene gas and the aqueous amine solution to the static mixer, and a separation step of separating the liquefied butadiene gas and the aqueous phase with a decanter. preferable.

  [F] In the washing step, it is preferable to add a polymerization inhibitor to the liquefied butadiene gas phase. As a polymerization inhibitor, hydroquinone, 4-methoxyphenol, phenothiazine, 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-hydroquinone, 4-t-butylcatechol, bisphenol A, etc. Is mentioned. The above polymerization inhibitors can be used alone or in combination of two or more.

[G] Drying Step The production method of the present embodiment preferably includes a drying step for removing water from the liquefied butadiene gas. Specifically, for example, in order to remove water from the liquefied butadiene gas introduced from the above step [f], the liquefied butadiene gas is supplied to the upper part of the distillation column, and water is extracted from the top of the column. Liquefied butadiene gas from which water has been removed is extracted from the bottom of the column. The pressure in this distillation is preferably 0.3 to 0.7 MPaG, more preferably 0.4 to 0.6 MPaG. The column top temperature in this distillation is preferably 40 to 60 ° C. The column bottom temperature in this distillation is preferably 45 to 90 ° C.
In the step [g], a tower such as a packed tower or a plate tower can be used.

  Water is distilled off at the top of the column by promoting the formation of the lowest azeotrope of water and butadiene. At the bottom of the column, butadiene and components having a boiling point higher than butadiene are concentrated. And, by increasing the temperature difference between the tower bottom and the tower top, it is possible to form distillation conditions that promote the distillation of azeotropic components, and to extract liquefied butadiene gas containing butadiene with reduced moisture content from the tower bottom. .

  Moreover, it is preferable to add a polymerization inhibitor in the step [g]. As a polymerization inhibitor, hydroquinone, 4-methoxyphenol, phenothiazine, 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-hydroquinone, 4-t-butylcatechol, bisphenol A, etc. Is mentioned. The above polymerization inhibitors can be used alone or in combination of two or more.

[H] Purification Step The liquefied butadiene gas that has flowed out from the above step [g] can be made into high purity butadiene by a known technique, for example, the method described in Japanese Patent No. 5687800.
Specifically, in the purification step, a distillation column for removing high boiling components from the liquefied butadiene gas flowing out from step [g], an absorption tower for removing C4 components other than butadiene, high purity butadiene (hereinafter referred to as “product butadiene”). It is preferable to install a stripping tower or the like that collects "." At this time, the product butadiene is preferably purified to a purity of preferably 98.0% or more, more preferably 99.0% or more.

[Butadiene production equipment]
The butadiene production method of the present embodiment can be performed by a butadiene production apparatus. That is, one of the embodiments is an apparatus for producing butadiene.
The apparatus for producing butadiene of this embodiment includes a reactor containing a catalyst containing a metal oxide and a carrier, a compressor that liquefies a reaction product gas containing butadiene to form liquefied butadiene, and liquefied butadiene as an aqueous amine solution. It is preferable to have a washing machine for washing. The washing machine preferably has, for example, a static mixer, an extraction tower, or a stirring mixer.

  Hereinafter, with reference to FIG.3 and FIG.4, the suitable aspect of the manufacturing apparatus of the butadiene of this embodiment is demonstrated in detail.

FIG. 3 is a diagram schematically illustrating an example of a butadiene production apparatus according to the present embodiment.
Specifically, a raw material gas containing n-butene and an oxygen-containing gas are supplied to the reactor 7 in the production apparatus.
The reaction product gas flowing out of the reactor is fed into the quenching tower 8 from the bottom, and is washed in contact with the quenching liquid in the quenching tower 8. The washed reaction product gas flows out from the top of the tower and is introduced into the bottom of the absorption tower 9.
The reaction product gas introduced into the bottom of the absorption tower 9 is absorbed by the absorption solvent (for example, xylene, mixed xylene or toluene) in the absorption tower 9, and flows out from the bottom of the tower as an absorption solvent containing butadiene. On the other hand, off-gas flows out from the top of the absorption tower 9. The absorbing solvent containing butadiene flowing out from the bottom of the absorption tower 9 is introduced into the diffusion tower 10.
After the solvent is separated from the absorbing solvent containing butadiene in the stripping tower 10, the crude butadiene gas flows out from the top of the tower and is supplied to the cooler 18 that performs the compression process. The crude butadiene gas becomes liquefied butadiene gas in the cooler 18 and is supplied to the drum 19.
In order to mix the liquefied butadiene gas flowing out from the drum 19 and the aqueous amine solution 20 and perform the washing process, the butadiene compound is supplied to the static mixer 3 to remove carbonyl compounds including acetaldehyde, and the decanter 21 performs oil-water separation.

The liquefied butadiene gas flowing out from the decanter 21 is supplied to the distillation column 11 and water is removed. The crude butadiene that has flowed out of the distillation column 11 is supplied to the middle stage of the first extractive distillation column 12.
In the first extractive distillation column 12, a solvent (for example, dimethylformamide) is sprayed from the top of the column, and a solution of crude butadiene is generated and flows out from the bottom of the column. The crude butadiene solution that has flowed out is introduced into the solvent separation tower 13 and, for example, butane is separated from the top of the tower.
In the solvent separation tower 13, the solvent of the crude butadiene solution is separated, and the crude butadiene flowing out from the top of the tower is introduced into the second extractive distillation tower 14. In the second extractive distillation column 14 as well, the solvent is sprayed from the upper part of the column like the first extractive distillation column 12, and a crude butadiene solution is generated. The second extractive distillation column 14 is operated at a temperature at which a component containing butadiene flows out from the column top and a solvent in which impurities such as acetylene are dissolved is separated from the column bottom. As a result, the crude butadiene flows out from the top of the second extractive distillation column 14.
When the low boiling point compound (for example, methylacetylene) and the high boiling point compound (for example, 2-butene) are separated from the crude butadiene flowing out of the second extractive distillation column 14 in the first distillation column 15 and the second distillation column 16, Purified butadiene 17 is obtained.

FIG. 4 is a diagram schematically showing another example of the apparatus for producing butadiene of the present embodiment. The reactor 7, the quenching tower 8, the absorption tower 9, the stripping tower 10, and the tower after the cleaning step in the apparatus shown in FIG. 4 are the same as those in the example shown in FIG.
After separating the solvent from the butadiene-containing solution in the stripping tower 10, a solution containing butadiene and water flows out from the top of the tower, is supplied to the compressor 22, and passes through the cooler 18, so that the crude butadiene gas is liquefied butadiene. It becomes gas and is supplied to the drum 19.

  In the example shown in FIGS. 3 and 4, the description of the compressor, drain pot, heat exchanger, etc. other than the compression step and the washing step is omitted, but these are necessary or efficient in operation of the apparatus. It can be added as appropriate for the purpose of effective use of heat. For example, referring to the apparatuses described in JP-A-60-193931, JP-A-2003-128595, and JP-A-2010-90082 adds a compressor, a drain pot, a heat exchanger, and the like. Effective above. These prior documents can also be referred to in terms of the operating temperature, pressure, type of solvent, etc. of the distillation column.

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples described below.

(Response results)
The n-butene conversion, butadiene selectivity, and yield used to express the reaction results were defined by the following equations, respectively.

(Contact time)
The contact time was defined by the following formula.

(Wherein, W represents the catalyst charge (g), F represents the raw material mixed gas flow rate (NL / hr, NTP conversion), T represents the reaction temperature (° C.), and P represents the reaction pressure (MPaG).)

(Reactor)
As a fluidized bed reaction type reactor, a SUS304 fluidized bed reactor having a tube diameter of 3 inches and a height of 950 mm was used. The oxygen-containing gas was supplied from the bottom of the reactor, and the source gas containing n-butene was supplied from a nozzle located 150 mm above the bottom of the reactor.

(Oxygen analysis)
Analysis of oxygen at the outlet of the reactor was performed by gas chromatography directly connected to the reactor (GC-8A (manufactured by Shimadzu Corporation), analytical column: ZY1 (manufactured by Shinwa Kako), carrier gas: helium, column temperature: constant at 75 ° C., TCD set temperature: 80 ° C.).

(Raw material gas containing n-butene)
BBSS or n-butene was used as a raw material gas containing n-butene.
BBSS has a C4 component composition molar ratio of 1-butene: 2-trans-butene: 2-cis-butene: isobutene: n-butane: isobutane: butadiene = 41.30: 17.70: 13.50: 5. .60: 16.10: 4.70: 1.10.
n-butene has a C4 component molar ratio of 1-butene: 2-trans-butene: 2-cis-butene: isobutene: n-butane: isobutane: butadiene = 98.00: 0.05: 0.05 : 0.85: 0.99: 0.03: 0.03.

(Analysis of unreacted products and reaction products)
Analysis of reaction products such as unreacted n-butene and butadiene, methacrolein was performed by gas chromatography (GC-2010 (manufactured by Shimadzu Corporation), analytical column: HP-ALS (manufactured by J & W), Carrier gas: helium, column temperature: after gas injection, held at 100 ° C. for 8 minutes, then raised to 195 ° C. at 10 ° C./min, then held at 195 ° C. for 40 minutes, TCD • FID (hydrogen flame ion) Detector) set temperature: 250 ° C.).

(Acetaldehyde analysis)
Gas chromatography (GC-2010Plus (manufactured by Shimadzu Corporation), analytical column: CP-Volamine (manufactured by J & W), carrier gas: nitrogen, column temperature: after gas injection, held at 130 ° C. for 8 minutes, then at 30 ° C./minute The temperature was raised to 245 ° C., and then kept at 245 ° C. for 20 minutes.
In order to analyze the removal effect of acetaldehyde by the aqueous amine solution, analysis was performed at the inlet and outlet of the process of washing the liquefied gas with the aqueous amine solution to analyze the concentration of acetaldehyde.

Example 1
(A) Reaction step A catalyst in which a mixed metal oxide having an atomic ratio of contained metals represented by Mo ₁₂ Bi _0.60 Fe _1.8 Ni _5.0 K _0.09 Rb _0.05 Mg _2.0 Ce _0.75 as a catalyst is supported on 50% by weight of silica It was used.
1980 g of the catalyst was placed in a fluidized bed reactor made of SUS304 having a tube diameter of 3 inches and a height of 950 mm. The source gas was BBSS, and the flow rate was 75 NL / hr. The oxygen-containing gas was a mixture of air and nitrogen, and the air flow rate was supplied at 228 NL / hr and the nitrogen flow rate was 617 NL / hr. The total flow rate F was 920 NL / hr.
The reaction was carried out under conditions of a reaction temperature (T) of 360 ° C. and a reaction pressure (P) of 0.05 MPaG to obtain a reaction product gas. At this time, the contact time with the catalyst was 5.0 (g · sec / cc).
100 hours after the start of the reaction, the obtained reaction product gas was analyzed. As a result, the conversion of n-butene was 95.5%, the selectivity of butadiene was 83.1%, and the butadiene yield was 79. 4%.

(B) Quenching step The reaction product gas obtained in the step (a) is a quenching portion (tube diameter 100 mm, tube diameter 200 mm, height 300 mm) located at the top of the quenching tower (made of SUS304). Having a height of 1000 mm) was introduced into the lower stage, and exhaust gas was obtained from the top of the quenching tower. The quenching section in the quenching tower is a three-stage type.
The liquid extracted from the tower bottom was sprayed at 90, 180, and 180 L / Hr, respectively, on the upper, middle, and lower stages of the three-stage quenching section. A 10% by weight aqueous sodium hydroxide solution was added to the middle stage spray so that the pH of the bottom extract was 7.6. Moreover, the spray liquid to the upper stage was sprayed by cooling to 47 ° C. by passing through a heat exchanger. At this time, the temperature of the exhaust gas from the top of the quenching tower was 53 ° C.

(C) Absorption process The exhaust gas obtained in the process of (b) above is the lower stage of an absorption tower (made of SUS304 having a tube diameter of 2.5 inches, a height of 3300 mm, and filled with Raschig rings of 5 mmφ * 5 mm inside the tower). Introduced. To the upper stage of this absorption tower, toluene cooled to 1 ° C. (boiling point: 139.1 ° C.) is supplied at 5.0 kg / Hr, brought into countercurrent contact with the exhaust gas introduced from the lower stage, and C4 component containing butadiene. Was absorbed in toluene. The toluene at 20 ° C. that absorbed the C4 component was extracted from the bottom of the column.

(D) Dissipation step Toluene that has absorbed the C4 component obtained in the step (c) is a diffusion tower (made of SUS304; pipe diameter 2.5 inches, height 3000 mm, inside the tower, Raschig ring of 5 mmφ * 5 mm) In the middle stage). The stripping tower was operated so that the pressure was 0.40 MPaG, the bottom liquid temperature was 175 ° C., and the top gas temperature was 45 ° C. A gas containing 50.2% by weight of butadiene was obtained from the top of the stripping tower. Toluene containing no butadiene was extracted from the bottom of the stripping tower at 5.0 kg / Hr and supplied to the absorption tower as an absorbing liquid for absorbing the C4 component in the step (c).

(E) Compression step The butadiene-containing gas obtained in the step (d) was cooled to 10 ° C. to obtain a liquefied butadiene gas. The liquefied butadiene gas contained 3000 ppm by weight of acetaldehyde.

(F) Cleaning step The liquefied butadiene gas 180g / Hr obtained in the step (e) and the amine aqueous solution 180g / Hr having a hydrazine concentration of 0.2% by weight are joined together by a pipe to obtain a static mixer (stock) This was supplied to a static mixer manufactured by Noritake Company Limited, model T (3) H-12R-S). The static mixer was operated such that the pressure was 0.4 MPaG and the temperature was 10 ° C.
The liquid flowing out from the static mixer was supplied to a decanter, oil-water separation was performed, and the content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was measured. As a result, the content of acetaldehyde was 7 ppm by weight. there were. Further, the loss amount of butadiene was 0.10 g / Hr.

(Example 2)
A liquefied butadiene gas was obtained from a decanter under the same conditions as in Example 1 except that the concentration of hydrazine in the step (f) of Example 1 was 1.0% by weight. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 4 ppm by weight. Further, the loss amount of butadiene was 0.11 g / Hr.

(Comparative Example 1)
The process up to step (e) described in Example 1 was performed under the same conditions as in Example 1.
The liquefied butadiene gas obtained in the step (e) is supplied at a rate of 180 g / Hr to the bottom of a water washing tower (made of SUS304; pipe diameter 3 inches, height 2500 mm, and Raschig ring is filled inside the tower). did. The washing tower was operated so that the pressure was 0.4 MPaG, and the temperature at the bottom and the top of the tower was 10 ° C. Water was supplied from the top of the washing tower at a rate of 400 g / Hr, and the liquefied butadiene gas was washed with water by making countercurrent contact with the liquefied butadiene gas supplied from the tower bottom. As a result of oil-water separation of the liquid extracted from the top of the washing tower and measuring the content of acetaldehyde contained in the obtained liquefied butadiene gas, the content of acetaldehyde was 22 ppm by weight. Further, the loss amount of butadiene was 1.10 g / Hr.

(Comparative Example 2)
The process up to step (e) described in Example 1 was performed under the same conditions as in Example 1.
The liquefied butadiene gas obtained in the step (e) is supplied at a rate of 180 g / Hr to the bottom of a water washing tower (made of SUS304; pipe diameter 3 inches, height 2500 mm, and Raschig ring is filled inside the tower). did. The washing tower was operated so that the pressure was 0.4 MPaG, and the temperature at the bottom and the top of the tower was 10 ° C. Water was supplied from the top of the washing tower at a rate of 50 g / Hr, and the liquefied butadiene gas was washed with water by making countercurrent contact with the liquefied butadiene gas supplied from the tower bottom. As a result of oil-water separation of the liquid extracted from the top of the water washing tower and measuring the content of acetaldehyde contained in the obtained liquefied butadiene gas, the content of acetaldehyde was 213 ppm by weight. Moreover, the amount of butadiene loss was 0.34 g / Hr.

(Comparative Example 3)
In the step (f) of Example 1, except that 180 g / Hr of water was supplied instead of 180 g / Hr of the aqueous amine solution having a hydrazine concentration of 0.2% by weight, the same conditions as in Example 1 were used. A liquefied butadiene gas was obtained. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 369 ppm by weight. The loss amount of butadiene was 0.12 g / Hr.

(Example 3)
In the step (f) of Example 1, except that 180 g / Hr of an aqueous amine solution having a monoethanolamine concentration of 1.0 wt% was supplied instead of 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.2 wt%, Under the same conditions as in Example 1, liquefied butadiene gas was obtained from the decanter. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 14 ppm by weight. Further, the loss amount of butadiene was 0.11 g / Hr.

Example 4
Example 1 except that 180 g / Hr of an aqueous amine solution with a butylamine concentration of 1.0 wt% was supplied instead of 180 g / Hr of an aqueous amine solution with a hydrazine concentration of 0.2 wt% in the step (f) of Example 1. Under the same conditions as in Example 1, a liquefied butadiene gas was obtained from a decanter. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 18 ppm by weight. Further, the loss of butadiene was 0.13 g / Hr.

(Example 5)
Example 1 except that 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.15 wt% was supplied instead of 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.2 wt% in the step (f) of Example 1. Under the same conditions as in Example 1, a liquefied butadiene gas was obtained from a decanter. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 21 ppm by weight. The amount of butadiene loss was 0.16 g / Hr.

(Example 6)
Example 1 is the same as Example 1 except that 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 10 wt% was supplied instead of 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.2 wt% in the step (f) of Example 1. Under the same conditions, liquefied butadiene gas was obtained from the decanter. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 3 ppm by weight. Moreover, the amount of butadiene loss was 0.08 g / Hr.

(Example 7)
Example 1 except that in the step (f) of Example 1, an aqueous amine solution having a hydrazine concentration of 0.2 wt% was replaced with 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.2 wt%, an amine aqueous solution having a hydrazine concentration of 0.5 wt% was supplied. Under the same conditions as in Example 1, a liquefied butadiene gas was obtained from a decanter. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 9 ppm by weight. Moreover, the amount of butadiene loss was 0.08 g / Hr.

(Example 8)
In Example 1 (f), except that 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.2% by weight was used, 400 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.2% by weight was supplied. Under the same conditions as in Example 1, a liquefied butadiene gas was obtained from a decanter. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 5 ppm by weight. The amount of butadiene loss was 0.44 g / Hr.

Example 9
Except for supplying 180 g / Hr of an aqueous amine solution having a hydrazine sulfate concentration of 0.2% by weight instead of 180 g / Hr of an aqueous amine solution having a hydrazine concentration of 0.2% by weight in the step (f) of Example 1, Under the same conditions as in Example 1, liquefied butadiene gas was obtained from the decanter. The content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter was 5 ppm by weight. Further, the loss of butadiene was 0.17 g / Hr.

(Example 10)
The catalyst amount in the step (a) of Example 1 is 1580 g, the raw material gas is n-butene, the n-butene flow rate is 75 NL / hr, the air flow rate is 295 NL / hr, and the nitrogen flow rate is 550 NL / hr. (Total flow rate F = 920 NL / hr) was supplied. At this time, the contact time with the catalyst was 4.0 (g · sec / cc).

  The analysis of the reaction product gas was performed as described above by gas chromatography directly connected to the reactor and the quenching tower. As for the reaction results 24 hours after the start of the reaction, the conversion of n-butene was 98.2%, the selectivity of butadiene was 88.6%, and the butadiene yield was 87.0%.

The steps (b), (c), (d), and (e) were performed under the same conditions as in Example 1 to obtain a liquefied butadiene gas. The liquefied butadiene gas contained 1000 ppm by weight of acetaldehyde.
The liquefied butadiene gas (180 g / Hr) obtained in the step (e) and the amine aqueous solution (180 g / Hr) having a hydrazine concentration of 0.2% by weight are joined together in a pipe to obtain a static mixer (manufactured by Noritake Company Limited). To a static mixer, model T (3) H-12R-S). The static mixer was operated such that the pressure was 0.4 MPaG and the temperature was 10 ° C.
The liquid flowing out from the static mixer was supplied to a decanter to perform oil-water separation, and as a result of measuring the content of acetaldehyde contained in the liquefied butadiene gas extracted from the decanter, the content of acetaldehyde was 5 ppm by weight. there were. Further, the loss amount of butadiene was 0.10 g / Hr.

(Example 11)
The process up to step (e) in Example 1 was performed under the same conditions as in Example 1.
The liquefied butadiene gas obtained in the step (e) is added to the bottom of the extraction tower (manufactured by SUS304; pipe diameter 3 inches, height 2500 mm, and Raschig ring is filled inside the tower) at a rate of 180 g / Hr. Supplied. The extraction column was operated so that the pressure was 0.4 MPaG and the temperature at the bottom and the top of the column was 10 ° C. An aqueous amine solution having a hydrazine concentration of 1% by weight is supplied from the top of the washing tower at a rate of 50 g / Hr, and the liquefied butadiene gas is supplied in an aqueous amine solution by countercurrent contact with the liquefied butadiene gas supplied from the bottom of the tower. Washed.
The liquid extracted from the top of the extraction tower was subjected to oil / water separation, and the content of acetaldehyde contained in the obtained liquefied butadiene gas was measured. As a result, the content of acetaldehyde was 17 ppm by weight. The amount of butadiene loss was 0.31 g / Hr.

  According to the production method of the present invention, high-purity butadiene can be produced and has industrial applicability in the field of synthetic rubber and resin raw materials.

1: Liquefied butadiene gas 2: Decanter 3: Static mixer 4: Waste liquid 5: Amine aqueous solution 6: Liquefied butadiene gas after removal of carbonyl compound 7: Reactor 8: Quenching tower 9: Absorption tower 10: Stripping tower 11: Distillation Column 12: First extraction distillation column 13: Solvent separation column 14: Second extraction distillation column 15: First distillation column 16: Second distillation column 17: Purified butadiene 18: Cooler 19: Drum 20: Amine aqueous solution 21: Decanter 22: Compressor

Claims (5)

a reaction step in which a raw material gas containing n-butene and an oxygen-containing gas are brought into contact with a catalyst in a reactor to obtain a reaction product gas containing butadiene;
A compression step in which the resulting reaction product gas containing butadiene is liquefied butadiene gas;
A cleaning step of cleaning the liquefied butadiene gas with an aqueous amine solution;
A process for producing butadiene.   The method for producing butadiene according to claim 1, wherein the aqueous amine solution is an aqueous solution containing hydrazines and / or organic amines.   The hydrazines are at least one selected from the group consisting of hydrazine, methyl hydrazine, ethyl hydrazine, and phenyl hydrazine, and their hydrochlorides, sulfates, and acetates thereof. A process for producing butadiene as described in 1. above.   The organic amine is at least one selected from the group consisting of monoethanolamine, methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, and t-butylamine. The manufacturing method of butadiene of description. The washing step
A mixing step of supplying the liquefied butadiene gas and the aqueous amine solution to a static mixer;
A separation step of separating the liquefied butadiene gas and the aqueous phase with a decanter;
The manufacturing method of the butadiene of any one of Claims 1-4 containing this.